Last year I began a journey into the world of the .300 Blackout that I intend to continue here. In my last three articles ( I, II, III ) about the cartridge, I documented the theory of use, supersonic abilities, and weapons built to use this fantastic cartridge.

To summarize my prior work in a few sentences, the .300 Blackout has become a serious choice for today’s consumer in supersonic form. The cartridge is able to launch a 120-125gr projectile at speeds of up to 2400fps from a 16” barrel and can utilize specialty ammunition that can deliver match-like performance at ranges of 500 or more yards with velocities upwards of 2800fps. The .300 Blackout is a fully mature, modern cartridge that allows a full range of use with only a barrel change on a standard 5.56mm weapon system and a serious ballistic upgrade at close to medium range over existing 5.56mm options.

In these articles, I will be discussing the original ideas behind the cartridge and the nature of the .300 Blackout as a subsonic cartridge while looking at other modern rounds in the same playing field. I also put together a custom AR pistol to test both …Read the Rest